On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells

Author:

Martin William1,Russell Michael J.2

Affiliation:

1. Institut für Botanik III, Heinrich-Heine Universitaet Dü sseldorf, Universitä tsstrasse 1, 40225 Dü sseldorf, Germany

2. Scottish Universities Environmental Research Centre, Scottish Enterprise Technology Park, Rankine Avenue, East Kilbride, Glasgow G75 0QF, UK ()

Abstract

All life is organized as cells. Physical compartmentation from the environment and self–organization of self–contained redox reactions are the most conserved attributes of living things, hence inorganic matter with such attributes would be life's most likely forebear. We propose that life evolved in structured iron monosulphide precipitates in a seepage site hydrothermal mound at a redox, pH and temperature gradient between sulphide–rich hydrothermal fluid and iron(II)–containing waters of the Hadean ocean floor. The naturally arising, three–dimensional compartmentation observed within fossilized seepage–site metal sulphide precipitates indicates that these inorganic compartments were the precursors of cell walls and membranes found in free–living prokaryotes. The known capability of FeS and NiS to catalyse the synthesis of the acetyl–methylsulphide from carbon monoxide and methylsulphide, constituents of hydrothermal fluid, indicates that pre–biotic syntheses occurred at the inner surfaces of these metal–sulphide–walled compartments, which furthermore restrained reacted products from diffusion into the ocean, providing sufficient concentrations of reactants to forge the transition from geochemistry to biochemistry. The chemistry of what is known as the RNA–world could have taken place within these naturally forming, catalyticwalled compartments to give rise to replicating systems. Sufficient concentrations of precursors to support replication would have been synthesizedin situgeochemically and biogeochemically, with FeS (and NiS) centres playing the central catalytic role. The universal ancestor we infer was not a free–living cell, but rather was confined to the naturally chemiosmotic, FeS compartments within which the synthesis of its constituents occurred. The first free–living cells are suggested to have been eubacterial and archaebacterial chemoautotrophs that emerged more than 3.8 Gyr ago from their inorganic confines. We propose that the emergence of these prokaryotic lineages from inorganic confines occurred independently, facilitated by the independent origins of membrane–lipid biosynthesis: isoprenoid ether membranes in the archaebacterial and fatty acid ester membranes in the eubacterial lineage. The eukaryotes, all of which are ancestrally heterotrophs and possess eubacterial lipids, are suggested to have arisenca. 2 Gyr ago through symbiosis involving an autotrophic archaebacterial host and a heterotrophic eubacterial symbiont, the common ancestor of mitochondria and hydrogenosomes. The attributes shared by all prokaryotes are viewed as inheritances from their confined universal ancestor. The attributes that distinguish eubacteria and archaebacteria, yet are uniform within the groups, are viewed as relics of their phase of differentiation after divergence from the non–free–living universal ancestor and before the origin of the free–living chemoautotrophic lifestyle. The attributes shared by eukaryotes with eubacteria and archaebacteria, respectively, are viewed as inheritances via symbiosis. The attributes unique to eukaryotes are viewed as inventions specific to their lineage. The origin of the eukaryotic endomembrane system and nuclear membrane are suggested to be the fortuitous result of the expression of genes for eubacterial membrane lipid synthesis by an archaebacterial genetic apparatus in a compartment that was not fully prepared to accommodate such compounds, resulting in vesicles of eubacterial lipids that accumulated in the cytosol around their site of synthesis. Under these premises, the most ancient divide in the living world is that between eubacteria and archaebacteria, yet the steepest evolutionary grade is that between prokaryotes and eukaryotes.

Publisher

The Royal Society

Subject

General Agricultural and Biological Sciences,General Biochemistry, Genetics and Molecular Biology

Cited by 640 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3